In enzymology, a maleimide hydrolase (EC 3.5.2.16) is an enzyme that catalyzes the chemical reaction

maleimide + H₂O maleamic acid

Thus, the two substrates of this enzyme are maleimide and H₂O, whereas its product is maleamic acid.

This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in cyclic amides. The systematic name of this enzyme class is cyclic-imide amidohydrolase (decyclizing). Other names in common use include imidase, cyclic imide hydrolase, and cyclic-imide amidohydrolase (decyclicizing) [misprint].

• Ogawa J, Soong CL, Honda M, Shimizu S (1997). "Imidase, a dihydropyrimidinase-like enzyme involved in the metabolism of cyclic imides". Eur. J. Biochem. 243 (1–2): 322–7. doi:10.1111/j.1432-1033.1997.0322a.x. PMID 9030755.